Soundproof window construction



Feb. 19, 1935. 5. J. ZAND' 1,991,832

SOUNDPROOF WINDOW CONSTRUCTION Filed May 18, 1933 INVENTOVR; 57FPH- J. ZHND oriNEY.

Patented Feb. 19, 1935 UNITED STATES;

PATENT OFFICE Sperry Gyroscope Company, N. Y., a corporation of New York Inc., Brooklyn,

Application May 18, 1933, Serial No. 671,622

Claims. (01. 20-564) This invention relates to means forlessening the noise and vibration in the cabins of aircraft, especially of the passenger carrying type. In aircraft now in use, the noise level is so high and the vibration so marked as to cause actual discomfort to the passengers and virtually prevent ordinary conversation. In the prior application of Preston R. Bassett and applicant, Serial No. 666,940, filed April 20, 1933 for Sound proof cabin for aircraft, there is disclosed a method of constructing the walls and framework of the cabin so as to prevent transmission of vibration within the cabin and shut out exterior noises. Even with such construction, however, a great deal cf exterior noises and vibration will be transmitted within the cabin through the window panes unless special window and window frame construction is adopted in connection with the sound proofing of the walls. This invention, therefore, primarily relates to the construction of the window glass holding frames and the construction of the pane itself whereby vibrations of the exterior shell of the cabin are not transmitted to the glass and whereby any sound vibrations reaching the glass are quickly damped out due both to the frame construction and the structure of the glass pane itself.

Referring to the drawing showing several forms my invention may assume,

Fig. 1 shows a typical cabin transport plane with the windows on the side and front thereof.

Fig. 2 is an enlarged sectional detail through the window frame showing the wall construction and the support for the pane.

Fig. 3 is an end elevation of therubber strip used to hold the window pane on each side.

. Fig. 4 is a section similar to Fig. 2 showing a second form of window pane support.

As explained in the aforesaid prior application, the walls of the cabin are constructed with supporting stringers to which is secured the exterior doped fabric covering or thin metal sheathing 2.

' The interior framework or wall 3 is spaced therefrom and between the same is interposed a layer 4 of corrugated soft material, such 'as seepack, resembling corrugated blotting paper. A soft interior trim 21 may also be used. At the window frames a block of light wood 5 or similar substance may be interposed which supports the in-' terior and exterior clamping blocks 6 and 7. Preferably a composite block is used composed of alternate layers'of wood 5' and felt 20 cemented together. Between said clamping blocks and the window pane 8, I interpcse slotted rubber strips 9 which are placed on all 01.1 sides of the pane so that at nopoint does the pane come in contact with the clamping blocks 6 and 7. Said strips 9 are preferably slotted as at 10 to receive and frictionally grip the edge of the window pane. To increase the resiliency of the strip, the slot may 5 be connected with an interior slot or axial bore 11 extending through the strip and which is connected to the slot 10 through a narrow channel 12.

In the preferred construction shown in Fig. 4, the clamping blocks 6 and 7 engage the strip 9 l0 somewhat below the bottom 13 of the window pane. This avoids tightly compressing the rubber strips against the glass which would be likely to transmit frame vibrations thereto, and on the other hand permits sufilcient lateral flexing of the rubber to damp out and avoid such vibration transmission andto effectively damp out any vibration in the glass that may be otherwise set up. Tight compression of the rubber against the pane is also avoided in the down direction in Fig. 4 by spacing the pane from the bottom of slot 10 and by the flexing of the lips 14 and 15. The clamping blocks also preferably extend upwardly above the top line of contact 16 with the rubber strip to protect the strip.

A similar result is secured with the construction shown in Fig. 2 wherein the clamps 6 and 'i' engage the rubber strip above or on line with the bottom of the window frame but only along comparatively narrow edges 34 and 35. The

clamping edge is made narrow so that the rubber, instead of being closely compressed against the glass, may be squeezed outwardly, thereby preventing the transmission of vibration and accomplishing similar results to that achieved with the 35 construction shown in Fig. 4. I also find it important to construct the window pane itself in such a manner as to reduce its sound transmitting and ringing" properties or, in other words, to increase its vibration damping coef- 0 ficient. To this end I prefer a window pane made up of alternating sheets of glass and of a plastic transparent compound, such as cellulose-nitrate products or of the cellophane group, which have a much higher damping coeificient than glass. My invention is distinguished, however, from ordinary shatter-proof glass usually comprising,

two comparatively thick sheets of glass held together by a thin sheet of cellulose compound. According to my invention, I employ a maximum thickness of cellulose compound to increase the damping coefficient and reduce the ringing properties and also reduce the weight of the pane with a minimum thickness of glass. Preferably the outermost layers 23 and 24 are of thin glass to surface hardness and smoothness and to mak 'e A third or middle thin pane of glass 23 may also be used to increase the stiffness and avoid theuse of too thick a sheet of cellulose. Between the glass panes I place two sheets of such celluloid 25 and 26, the whole being firmly pressed together to form a single united sheet as is understood in the art. Such a pane has a much higher coefficient of damping than a single plate glass pane or than a pane resembling the usual safety glass, since I employ a muc greater proportion of celluloid, preferably in the form of several sheets, each preferably thicker than that usually employed, and much thinner panes of glass. For example, for a built up composite pane of thick overall, I employ three glass panes of thick each and two celluloid sheets thick each. Another example is a composite pane 2.5 mm.-thick of which all five sheets (glass and celluloid) are about .5 mm. thick. Not only is such a pane superior to the ordinary shatterproof glass in its noise absorbing qualities but- I have also found it much superior in shatter proof qualities in that the thinner panes of glass are less likely to splinter or fly off when a violent blow is given the same. The cracks developed are much finer and with less jagged edges.

In accordance with the provisions of the patent statutes, I have herein described the principle and operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention can be carried out by other means. Also, while it is designed to use the various features and elements in the combination and relations described, some of these may be altered and others omitted without interfering with the more general results outlined, and the invention extends to such use.

' Having described my invention, what I claim and desire to secure by Letters Patent is:

1. A sound proof window construction for airthe whole pane stiff and prevent buckling.

craft cabins and the like comprising slotted strips of rubber adapted to receive the edge of the pane for a part only of the depth of the slot, and

clamping means on the window frame adapted to grip the strips below the lower edge of the pane but above the lower end of the slot for the purpose specified.

2. A sound proof window construction for aircraft cabins and the like comprising slotted strips of rubber adapted to receive the edge of the pane,

the base of each slot being connected beyond said pane edge with a narrow slot merging into a larger slot, and clamping means on the window frame adapted to grip said strip without compressing a suflicient area of rubber directly against the pane with sufficient pressure to transmeans on the window frame adapted to grip the strips below the lower edge of the pane adjacent the base of the first named slot and above said larger slot for the purpose specified.

4. A sound proof window construction for aircraft cabins and the like comprising slotted strips of rubber adapted to receive the edge of the pane, and clamping means on the window frame adapted to grip the strips along narrow edges adjacent .the bottom of said pane and said pane being spaced from the bottom of said slots for the purpose specified.

5. A sound proof window construction for aircraft cabins and the like comprising slotted strips of rubber adapted to receive the edge of the pane for a part only of the depth of the slot, and clamping means on the window frame adapted to grip said strip opposite an intermediate portion of said slot and without compressing a sufficient area of rubber directly against the pane to transumit major vibrations.

STEPHEN J. ZAND. 

